stuscoredic={'张三':90,'李四':89,'王五':89}

#最高分同学
maxscore=max(stuscoredic.values())
for va, vb in stuscoredic.items():
    if vb==maxscore:
        print(va, vb)


#所有学生平均分
con=0
sumscore=0
for i in stuscoredic.values():
    sumscore=sumscore+i
    con=con+1
avg=sumscore/con
print(avg)
#求最低分的两个同学
minscore=min(stuscoredic.values())
for va, vb in stuscoredic.items():
    if vb==minscore:
        print(va, vb)

isfirst = True
for itm in stuscoredic.items():
   if isfirst :
        maxItem1=itm
        maxItem2= itm
        isfirst =False
   else:
       if maxItem1[1]<itm[1] :
           maxItem1=itm;
       elif  maxItem2[1]<itm[1] :
           maxItem2=itm
print(maxItem1)
print(maxItem2)